A typical wireless communication system includes wireless terminals and base stations. In such a wireless communication system, each base station provides a wireless area where a wireless terminal communicates with the base station, using a wireless resource.
A wireless terminal positioned in a wireless area executes random access to establish communication with a base station. Random access includes a process to send a preamble to a base station from the wireless terminal, using a wireless resource allocated by the base station in advance.
A preamble is a signal having a prescribed pattern. The base station calculates a degree of correlation between a signal received through a wireless resource allocated to preamble communication and a replica signal that the base station retains in advance, and detects a preamble on the basis of the calculated degree of correlation. Upon detection of a preamble, the base station sends a response signal corresponding to the detected preamble.
An example of such a wireless communication system allocates different wireless resources to preamble communication in respective neighboring wireless areas (see Patent Literature 1 and Patent Literature 2).
Patent Literature 1: Japanese National Publication of International Patent Application No. 2013-502810
Patent Literature 2: Japanese Laid-Open Patent Publication No. 2010-183287